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Add demo for logarithmic histogram plotting and fix rendering (#740) #1886

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Merged
VisualMelon merged 4 commits into from
Aug 13, 2022
Merged

Add demo for logarithmic histogram plotting and fix rendering (#740) #1886

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6cdae75
Add demo for logarithmic histogram plotting and fix rendering (#740)
FabianNitsche May 8, 2022
1e78758
Fix UpdateMinMax for logarithmic scale in HistogramSeries.
FabianNitsche May 9, 2022
2c14b82
Omit invalid values in HistogramSeries when using logarithmic scale.
FabianNitsche May 9, 2022
a97895a
Fix typo in UpdateMaxMinXY for HistogramSeries.
FabianNitsche May 9, 2022
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1 change: 1 addition & 0 deletions CHANGELOG.md
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Expand Up @@ -23,6 +23,7 @@ All notable changes to this project will be documented in this file.
- Code generation for escape sequences in strings (#1824)
- Axes not always honoring AbsoluteMinimum/AbsoluteMaximum and/or MinimumRange/MaximumRange properties (#1812)
- WindowsForms tracker no longer clipping outside PlotView boundaries (#1863)
- Histogram now rendering properly when using logarithmic Y axis (#740)

## [2.1.0] - 2021-10-02

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1 change: 1 addition & 0 deletions CONTRIBUTORS
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Expand Up @@ -49,6 +49,7 @@ Elia Herzog
Elmar Strittmatter
episage <tilosag@gmail.com>
eric
Fabian Nitsche <ifab@freenet.de>
Federico Coppola <fede@silentman.it>
Francois Botha <igitur@gmail.com>
Frank Tore Sæther <frank.sather@gmail.com>
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16 changes: 13 additions & 3 deletions Source/Examples/ExampleLibrary/Series/HistogramSeriesExamples.cs
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Expand Up @@ -29,6 +29,13 @@ public static PlotModel ExponentialDistribution()
return CreateExponentialDistribution();
}

[Example("Exponential Distribution (logarithmic)")]
[DocumentationExample("Series/HistogramSeries")]
public static PlotModel ExponentialDistributionLogarithmicAxis()
{
return CreateExponentialDistribution(true);
}

[Example("Label Placement")]
public static PlotModel HistogramLabelPlacement()
{
Expand Down Expand Up @@ -122,10 +129,13 @@ public CustomHistogramItem(double rangeStart, double rangeEnd, double area, int
public string Description { get; }
}

public static PlotModel CreateExponentialDistribution(double mean = 1, int n = 10000)
public static PlotModel CreateExponentialDistribution(bool logarithmicYAxis = false, double mean = 1, int n = 10000)
{
var model = new PlotModel { Title = "Exponential Distribution", Subtitle = "Uniformly distributed bins (" + n + " samples)" };
model.Axes.Add(new LinearAxis { Position = AxisPosition.Left, Title = "Frequency" });
var model = new PlotModel { Title = logarithmicYAxis ? "Exponential Distribution (logarithmic)" : "Exponential Distribution", Subtitle = "Uniformly distributed bins (" + n + " samples)" };
model.Axes.Add(
logarithmicYAxis ?
(Axis)new LogarithmicAxis { Position = AxisPosition.Left, Title = "Frequency"} :
new LinearAxis { Position = AxisPosition.Left, Title = "Frequency" });
model.Axes.Add(new LinearAxis { Position = AxisPosition.Bottom, Title = "x" });

Random rnd = new Random(1);
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19 changes: 16 additions & 3 deletions Source/OxyPlot/Series/HistogramSeries.cs
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Expand Up @@ -244,8 +244,16 @@ protected internal void UpdateMaxMinXY()
{
this.MinX = Math.Min(this.ActualItems.Min(r => r.RangeStart), this.ActualItems.Min(r => r.RangeEnd));
this.MaxX = Math.Max(this.ActualItems.Max(r => r.RangeStart), this.ActualItems.Max(r => r.RangeEnd));
this.MinY = Math.Min(this.ActualItems.Min(r => 0), this.ActualItems.Min(r => r.Height));
this.MaxY = Math.Max(this.ActualItems.Max(r => 0), this.ActualItems.Max(r => r.Height));
if (this.YAxis.IsLogarithmic())
{
this.MinY = Math.Max(this.ActualItems.Min(r => r.Height), double.Epsilon);
this.MaxY = Math.Max(this.ActualItems.Max(r => r.Height), double.Epsilon);
}
else
{
this.MinY = Math.Min(this.ActualItems.Min(r => 0), this.ActualItems.Min(r => r.Height));
this.MaxY = Math.Max(this.ActualItems.Max(r => 0), this.ActualItems.Max(r => r.Height));
}
}
}

Expand Down Expand Up @@ -295,10 +303,15 @@ protected void RenderBins(IRenderContext rc, ICollection<HistogramItem> items)
{
foreach (var item in items)
{
if (this.YAxis.IsLogarithmic() && !this.YAxis.IsValidValue(item.Height))
{
continue;
}

var actualFillColor = this.GetItemFillColor(item);

// transform the data points to screen points
var p1 = this.Transform(item.RangeStart, 0);
var p1 = this.Transform(item.RangeStart, this.YAxis.IsLogarithmic() ? double.Epsilon : 0);
var p2 = this.Transform(item.RangeEnd, item.Height);

var rectrect = new OxyRect(p1, p2);
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